MnDRIVE Aims to Spark New Collaborations into Sustainable Plastics

Researchers at the University of Minnesota and their counterparts in industry are discussing new ways to work together in search of solutions for the mounting problem plastic waste poses across the globe.

In addition to developing technologies to break down plastics that find their way into the environment, MnDRIVE Environment researchers are now exploring how to replace traditional petroleum-based plastics and polymers with bio-based alternatives. The key, though, is finding replacements that not only perform as well as traditional plastics but also harmlessly biodegrade or breakdown during recycling to enable reuse. 

The MnDRIVE effort builds upon existing UMN research into sustainable plastics, such as the work of the Center for Sustainable Polymers, and includes researchers from across campuses, colleges, and disciplines. Experts from industry are also getting involved to lend their expertise and address considerations like sustainable food packaging and how to reduce the amount of new plastic (versus recycled) used in their operations.

Increasing the research focus on plastics comes in response to a dire need. While landfills took in 27 million tons of plastic in 2018, according to the Environmental Protection Agency, plastic waste isn’t constrained to the dump.

“We find plastics pretty much everywhere now—in our oceans, our lakes, our soils, groundwater, raining on us from the air,” said Jeff Standish, PhD, industry and government liaison for MnDRIVE Environment, at a recent virtual listening session designed to kick off new collaborations. “And we see a huge range in the type of plastics and also the size of plastics that we’re identifying. This quickly turns the conversation about recycling and remediation into a very complex discussion.”

With Plastics, It’s Complicated

Plastics span a broad array of chemical compounds that have very different properties and uses, said Brett Barney, PhD, a MnDRIVE researcher and associate professor of bioproducts and biosystems engineering in the College of Biological Sciences and College of Science and Engineering. In addition to the solid plastics used to manufacture products, there are polymers in fields like medicine and water treatment that may take the form of powders, emulsions, or solutions.

This variety of materials, combined with their long names (like polyethylene terephthalate) and acronyms, can leave the average consumer confused over how to sort materials for recycling. Even the recycling numbers stamped on the materials themselves don’t provide a perfect guide, as many products combine different types of plastics to take advantage of each one’s unique properties. A typical plastic soda bottle, for example, might include four different categories of plastic between the material used in the cap, the rubber gasket, the body of the bottle, and the label wrapped around it. Each one needs to be separated during the recycling process.

“This level of complexity serves as a tremendous obstacle towards implementing cost-effective and economical recycling activities and educating consumers on how to pre-sort certain plastics,” Barney said.

Even the relatively recent additions of bioplastics and biopolymers can mislead people, he noted, as “green plastics” aren’t inherently sustainable.

“You can legitimately produce plastics from plants and call them ‘green,’ but this does not mean they are inherently biodegradable,” Barney said. “This means that these plastics are not derived from oil, but it does not alter the issue of how to recycle or dispose of them.”

Some plastics are more susceptible than others to being degraded in nature by various types of microbes. Barney’s lab, collaborating with other UMN researchers and students at Minnesota high schools, is now exploring whether certain species of bacteria and fungi can break down some of these more difficult-to-degrade plastics.

Seeking Perfect Polymers

Research into plastics should be about more than fixing existing problems, said Paul Dauenhauer, PhD, professor of chemical engineering and materials science in CSE, senior investigator in the Center for Sustainable Polymers, and recently named MacArthur Foundation fellow. The plastics problem presents an opportunity for scientists to imagine what perfect plastics and polymers might look like—and what it would take to make them reality.

“If we start making new materials, why not make better polymers that give us either better properties or more recyclable capabilities?” he said.

On the front end, improving these materials means using renewable source material (such as corn, trees, grasses, soybeans, or other forms of plant matter) as the basis for the monomers (“small” chemicals) that bond together to form the polymer. It also means matching or even undercutting the price tag on existing, oil-based materials so they can compete in the market.

The other half of the plastics equation is what happens after production. Melissa Maurer-Jones, PhD, assistant professor in the Swenson College of Science and Engineering at University of Minnesota Duluth, aims to address part of that question by studying how plastics break down under different kinds of environmental stressors. Understanding how the properties of polymers change as they decompose in nature will help researchers gauge their negative effects and make changes to prevent those effects.

“Sustainable solutions require a complete understanding of the end-of-life of our designed materials,” Maurer-Jones said. “Understanding and quantifying these different transformations allows us to design polymers with desired properties with minimal environmental impact.”

Other areas of current research include engineering bacteria capable of degrading common plastics and improving recycling processes themselves. Pyrolysis technologies are one potential avenue, Dauenhauer said, as they use heat to break up a diverse mixture of plastics and convert them to a liquid commodity. This liquid could potentially be sold or transported as needed and then further reduced to ethylene and propylene—the building blocks of two very common plastic varieties.

Overall, better polymers means making the components used in everything from plastic bottles to car tires to detergents more functional, lower cost, and better for the environment, Dauenhauer said.

“What I would like in that perfect polymer system is a highly efficient process that will make the chemicals, make the polymer, but also build into that polymer the ability to be recycled back to the monomer that we started with,” he said. “At the same time, if that polymer gets into the environment, I would like it to biodegrade, where it would be out of the environment and into the atmosphere, where it could then be recovered by photosynthesis.”